Wireless communication with unmanned aerial vehicles (UAVs) has been adopted widely in air-ground integration network for military, public and emergency applications [1]}.
Compared with the terrestrial communication system, UAV-based air-ground network is not only easy to deploy, but also has better wireless channels [2]}.
Therefore, numerous UAV-based wireless communication systems have been developed [3]}, [4]}, [5]}, [6]}.
One typical application is the UAV-based data collection network in the air-ground IoT system, where UAV is deployed as a UBS flying over the IoT devices to collect the information.
In this way, the system avoids the complex routing design and improves the efficiency of data collection greatly.
However, there are still some challenges in developing UAV-based data collection system.
